Support is requested for a Keystone Symposia meeting entitled Hematopoiesis, organized by Timm Schroeder, Hanna K.A. Mikkola and Patricia Ernst. The meeting will be held in Keystone, Colorado from February 22-27, 2015. Over the past few decades, we have uncovered many important principles regarding development, proliferation, survival and lineage choice in the hematopoietic system. Integration of years of hematological clinical experience with basic hematopoiesis research has established principles and approaches that have informed many other fields, and continue to push technological and conceptual advances in both basic and clinical research. In this tradition, this Keystone Symposia meeting will bring together a spectrum of basic to clinical researchers who cover various aspects of hematopoiesis encompassing stem and progenitor cell development, maintenance and differentiation during homeostasis, stress and disease. How these processes are governed by signaling pathways, epigenetic mechanisms, transcriptional and miRNA networks, metabolic and local or systemic niche factors will be discussed by experts from different career stages and continents. The integration of innovative tools such as single cell quantification and novel imaging technologies in different model systems will be an important aspect throughout the meeting. In recent years, there has been renewed excitement in analyzing basic mechanisms of hematopoiesis which led to a greatly improved understanding of the embryonic and adult hematopoietic cellular hierarchy and of the molecular control of hematopoiesis. Due to the clinical experience in hematology, some of these discoveries have very quickly been translated into therapeutic approaches that are already tested in clinical trials This meeting will provide a forum for cross- fertilization between investigators pursuing diverse approaches such that participants benefit from latest technological developments and insights from different model systems, and pursue their research challenges with new insight and collaborations.